wick
芯 centers on the central, essential part of something: a wick is the core of a candle or lamp that draws fuel and sustains the flame.
芯 combines the grass radical 艹 on top with 心 (heart) below. The grass radical suggests a plant-derived fiber, while 心 (heart) reinforces the idea of a central core, like a wick at the heart of a lamp.
The grass 艹 on top represents the fibrous plant material of a wick, and the heart 心 below is the core that keeps the flame alive. Together, 芯 is the wick—the essential center.
For シン, imagine the thin wick burning at the center of a candle: thin -> シン, and the wick is the thin core that sustains the flame.
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wick; marrow; staple (for stapler); (pencil) lead; stuffing; pith
mechanical pencil lead
staple (for a stapler)
lamp wick
apple core; core of an apple
thick obi sash; sash padding
toilet drain outlet
spare pencil lead; pen refill (cartridge); replacement wick (e.g. of a lantern)
dead center (of a baseball bat); sweet spot
dead center
Chinese water spinach (Ipomoea aquatica); ong choy; kang kong; water morning glory; water convolvulus; swamp cabbage; hung tsai; rau muong; pak boong; swamp morning-glory
cardboard tube
mentally strong; strong-willed
to get to the heart of the matter; to get to the core
pencil lead case (for a mechanical pencil)
centering; center alignment
lead pointer (for a clutch pencil); lead sharpener
padding; lining; foundation
wick of a candle
collar core (stiff fabric, etc. inside a collar)